Exothermic steam generator



W. D. EGBERT ETAL 3,425,316 EXOTHERMIC STEAM GENERATOR Feb. 4, 1969 Filed Aug. 4. 1967 Sheet 0f 2 1969 w. 0. EGBERT ETAL 3,425,316

EXOTHERMIC STEAM GENERATOR Z of 2 Sheet Filed Aug. 4, 1967 wax/4M D TOR; BRI/AN' s: JwxaN 54 Q grzfazym United States Patent 5 Claims ABSTRACT OF THE DISCLOSURE An exothermic steam generator for cold launching a silo-based missile or rocket having an outlet through which high pressure steam escapes in order to launch the missile upon the actuation of two separate signals.

This invention relates generally to exothermic steam generators, and more particularly to exothermic steam generators used for the purpose of launching silo-based missiles or rockets.

The primary purpose of rocket and missile launchers is to support the rocket or missile in the correct position before the ignition of its propulsion elements. For several types of rockets and missiles, this position is the one required for giving it a trajectory aimed toward the desired target. However, for some types (particularly ballistic missiles) the position of the missile at the launching is vertical and all the guidance toward the target is brought into play later. For certain other types of rockets the launcher also provides a support along which the projectile travels until it picks up sufficient velocity for stable flight.

Outstanding features of launchers for small rockets and missiles are their simplicity, lightness of weight, and low cost. These characteristics are due in large measure to the lack of recoil in a rocket or missile at launching. Unlike guns, which give enough recoil to limit the size of projectiles which can be fired from planes, ships or a mans shoulder, the rocket makes it possible to fire payloads several hundred times those possible in gun-fired shells. The launchers of the largest missiles (such as I RBMs and ICBs) are quite simple when viewed in relation to their mission, but they are surrounded by an involved complex of support equipment. The latter becomes particularly intricate in the case of large liquidfueled missiles, where propellant handling and monitoring are major phases of the launching operations. These launchers are primarily located at what is known as a missile or rocket launching site.

A ballistic missile site erected above ground is known as a soft base. It is so called because it is vulnerable to missile or bombing attacks and could be crushed easily by a blow directed upon it. Despite their vulnerability, all launching sites, which were in use before the early l960s, are of this character. This situation is natural because it is easier to locate the various launch facilities above ground than to arrange them in some other form. Those missiles, now ready for operational service, have been brought to a state of readiness most expeditiously by utilizing fixed launch facilities placed directly around them on the earths surface. In the case of space launching vehicles, there is no need to take military base precautions, so they will probably continue to be launched from above surface installations.

In soft base installations, the missiles are kept in shelters which can be retracted at the time of an alert. The missile is then erected, checked, fueled, and fired. For liquid-fueled missiles, the propellants are stored above ground in cylindrical tanks on either side of the launching pad.

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The primary disadvantage of a soft base is that even a near miss of an atomic or hydrogen bomb would seriously impair the capability of a complex missile launching site of the soft or above ground type. Hence, a major program has been undertaken by the U3. Air Force to place these facilities underground. Such an installation is known as a hard base. The missiles are stored there in a silolike emplacement. Maintenance, checkout, and fueling operations are carried out in the underground silo. Then doors at the top of the silo are opened and the missile is either brought to the surface just prior to launching or fired directly from below the surface. Countdown operations are conducted in a blockhouse adjacent the silo.

The most spectacular and usually the most difiicult aspect of launching is the acceleration of the missile from a condition of rest with respect to the launcher to flight speed. The accelerating force is provided by auxiliary solid or liquid propellant motors, by gasor steam-powered catapult, or by the missile motor itself.

Auxiliary jet motors used only to accelerate the missile from the launcher to some predetermined flight speed are referred to as JATO or booster motors. By rigorous definition a JATO motor is a self-contained auxiliary jet motor having a definite burning time and a fixed thrust.

Solid propellant motors are well adapted for use as JATOs. They are compact; their handling, shipping and stowage requirements are not very severe; they can be manufactured in a wide range of sizes; their shapes and sizes are readily adaptable to missile-booster configurations; and they are not unduly affected by considerable variation in their atmospheric environment. Their major disadvantages are: inflexibility to varying missile requirements, high unit cost because of elaborate manufacturing and inspection procedures, high transient thrusts superimposed on the steady-state characteristics, and some explosion hazard. Also, some grain formulations have limited storage life.

While JATOs are very convenient, self-contained power packages for applying accelerating forces to missiles, there are situations where a catapult could be used to better advantage. A catapult is simply an engine for repeatedly providing an accelerating force. From the missile standpoint the most important difference in the two launching techniques is that the accelerating force of the catapult, because of practical limitations of catapult length, must be applied over a shorter time interval than is necessary with JATOs. Consequently, the accelerating force must be greater to provide a given missile end speed. Further, the end speed must be Well above stalling speed because the missile is launched in proximity to the ground plane. The higher accelerations impose more severe stresses on the missile structure and components.

Missiles having a low stalling speed or which are very rugged may be economically and conveniently launched by catapult, particularly if they are of large size. This is because of the high unit cost of JATOs compared to the propellants and simple sleds required by catapults and because of the more severe logistics requirements of manufacturing, stowing, and handling JATOs compared to the catapult propellants. Opposed to these advantages are the high initial costs of manufacture and installation of catapults and their vulnerability to battle damage or destruction. High rates of fire can be better obtained through JATO launchings from a number of relatively inexpensive launchers than by any conceivable operational procedure with catapults.

The missile or rocket launching system of this invention overcomes a majority of previously described launching problems encountered with the JATO and catapult type launching systems. This missile or rocket launching system uses the energy storage tank concept of an exothermic steam generator to cold launch a silo-based missile or rocket. The energy storage tank is a device which generates high pressure water, or low quality steam at high pressures, and then releases this fluid at a controlled rate. When the fluid is released into a closed breech tube beneath a missile it flashes to steam with resultant expansion forcing the missile from the tube. Although the exothermic steam generator missile launching system of this invention is to be used primarily with silo-based missiles or rockets, it is not to be restricted to silo-based missiles or rockets. It can be modified by one of ordinary skill so as to be used with missiles or rockets launched from soft or above ground sites, as well as those below.

It is the primary object of this invention to provide an exothermic steam generator for cold launching a silobased missile or rocket.

Another object of this invention is to provide an exothermic steam generator which is simple to operate and which is extremely reliable.

It is a further object of this invention to provide an exothermic steam generator which is capable of meeting a wide range of performance requirements.

It is still a further object of this invention to provide an exothermic steam generator which requires two separate starting signals.

Another object of this invention is to provide an exothermic steam generator which is extremely safe because of the nonexplosive reaction of the exothermic charge.

Still another object of this invention is to provide an exothermic steam generator which substantially eliminates the inadvertent launch of a missile because of the requirement for two independent signals to release the steam necessary for launch.

It is a further object of this invention to provide an exothermic steam generator which is economical to produce and which utilizes conventional, currently available components that lend themselves to standard mass production manufacturing techniques.

For a better understanding of the present invention, together with other and further objects thereof, reference is had to the following description taken in connection with the accompanying drawings and its scope will be pointed out in the appended claims. In the drawings:

FIGURE 1 is a partially sectioned side elevation of the exothermic steam generator according to the invention;

FIGURE 2 is a side elevation of a modification of the exothermic steam generator shown in FIGURE 1 partially sectioned; and

FIGURE 3 is a sectional view in side elevation showing the exothermic steam generator of this invention in combination with a rocket launching tube in operating position.

Referring to FIGURE 1 of the drawing, there is shown an exothermic steam generator for cold launching a silo-based missile or rocket 12 (shown in FIGURE 3). The exothermic steam generator 10 comprises a pressure vessel 11 having an outer shell 14, preferably of steel, but which can be fabricated of any other suitable material; a coating of any suitable insulation 16, such as RTV silicone rubber; and an inner shell 18 of suitable material, such as stainless steel for protecting the insulation 16 from deteriorating and, therefore, eliminating the need of replacing the insulation 16 after a series of launches. Construction costs could be substantially reduced by eliminating both the insulation 16 and inner shell 18; however, the generator efficiency would suffer considerably.

Within the pressure vessel 11 is a central portion or chamber 20, a series of exothermic charge cylinders 30 and a liquid 32, preferably water. Contained within the chamber 20 is a cylinder 21, a valve or piston 22, a plurality of O-rings 23 which act as a seal, a valve motor 42 and outlets 24, 25, 26 and 28.

The exothermic charge contained within each cylinder 30 is basically made of two materials that may be identified as 'a fuel and an oxidizer. Aluminum and magnesium are suitable for use as fuels since they are highly energetic, low in cost and yield oxides which have welldefined properties. Studies demonstrated that manganese oxide, ferric oxide and tungsten oxide are suitable for use as oxidizers since they have satisfactory basic properties pertaining to processing, handling and ignition characteristics. Although the above materials are recommended as suitable fuels and oxidizers the exothermic charges are not limited to their use and any suitable equivalent may be substituted in their place.

The charge cylinders 30 are mounted on supports 34 by any suitable securing means such as bolts and each charge cylinder 30 is ignited by means of an ignited assembly. The igniter assembly is comprised of a suitable starter 31 such as tungsten oxide powder spread over the end of charge cylinder 30, a suitable igniter 33 such as a nailhead squib, a cable 36 and a switch or starting means 37 which is connected to a power source (not shown) for conventional squib ignition. The starter 31 is fired by means of the igniter 33. The charge cylinder 30, starter 31, igniter 33 and cable 36 are covered by a suitable water-tight protective covering 35 such as polyethylene to preclude prewetting of the charge prior to ignition. The cable 36 connects the igniter 33 to the switch or starting means 37 located externally of the pressure vessel. These charges may be fired individually or in combination, depending upon the amount of charge required by activating the switch or starting means 37.

The valve or piston 22 is operated by any suitable valve motor 42. One such valve motor suitable for operating valve 22 comprises a piston rod 38 attached to valve or piston 22 at one end thereof and piston 44 at the other end thereof. The piston 44 is air-biased to either a position shown in FIGURE 1, in which outlets 25 are closed by valve 22, or an up position in which outlets 25 are open. The air supply which biases the piston 44 up or down is controlled by a solenoid (not shown) located externally of the pressure vessel and operably connected to valve motor 42 by means of lines 45.

There is an access cover 46 located on the top surface of the pressure vessel 11. Mounted directly above outlet 28 and adjacent cover 46 is a launch tube 48 wherein the missile or rocket 12 to be launched is located (see FIG- URE 3).

The launching tube 48 with steam generator 10 attached thereto is mounted within the silo 50 beneath launching doors 52 by any suitable mounting means such as supports 51 (see FIGURE 3). When the missile or rocket 12 is ready to be fired a first signal initiates the charge reaction by activating switch 37 (shown in FIG- URE 1). The ensuing chemical reaction raises the temperature and pressure of the water or liquid 32 within the vessel 11. A second signal actuates valve motor 42 which raises valve 22 opening outlets 25. The liquid 32 begins to flow through outlets 24 and 25 thus lowering the pressure within vessel 11. This drop in pressure causes the water or liquid 32 within vessel 11 to transform to high pressure steam. The high pressure steam then passes through outlets 24, 25, 26 and 28 to launch the missile or rocket 12 which rests above outlet 28 in launch tube 48.

Referring to FIGURE 2, there is shown an exothermic steam generator of modified construction. The generator 54 is basically the same as steam generator 10 (shown in FIGURE 1) and will therefore have the same reference numerals designating identical parts. Steam generator 54 has only two sets of outlets 56 and 58. The pressure vessel 13 of generator 54 is the same as the pressure vessel 11 of exothermic steam generator 10 and is therefore accordingly numbered; outer shell 14, insulation 16 and inner shell 18. The pressure vessel 13 also has an access cover 46 associated therewith.

Within the pressure vessel 13 is a central portion or chamber 20, a series of exothermic charge cylinders 30 and a liquid 32, preferably water. Contained Within the chamber 20 is a cylinder 21, a plurality of O-rings 23 which act as a seal, a valve or piston 60, a valve motor 66 and outlets 56 and 58.

In steam generator 54, the valve or piston 60 is located toward the top of the pressure vessel 13. The valve motor 66 drives valve or piston 60 to the position shown in FIG- URE 2 in order to close outlet -56 or to the down position to open outlet 56. The valve motor 66 may be of any suitable construction such as a type of valve motor 42 described in conjunction with generator shown in FIGURE 1. The exothermic charge cylinder 30, the charge therein, the starter 31, the igniter 33, the protective covering 35, the cable 36 and the switch or starting means 37 are either identical to those used with exothermic steam generator 10 or may be of any other suitable design.

Referring again to FIGURE 2, a first signal initiates the charge reaction in charge cylinder 30 which raises the temperature and pressure of the water or liquid 32- in vessel 13. A second signal actuates valve motor 66 which lowers valve 60 opening outlets 56. The opening of outlets 56 lowers the pressure within vessel 13. This drop in pressure within vessel 13 causes the water or liquid 32 therein to transform to high pressure steam. The high pressure steam then passes through outlets 56 and 58 in order to launch the missile or rocket 12 situated in the launch tube 48 (see FIGURE 3).

Exothermic steam generator '54 externally is identical to generator 10. These steam generators, therefore, may be readily interchanged and mounted in identical silos 50 by means of supports 51 (see FIGURE 3).

A typical launching operation will now be described using as an example exothermic steam generator 10 mounted within silo 50.

The charge cylinders 30 are mounted in place and the exothermic steam generator '10 is filled with a liquid 32 such as water. With the missile or rocket 12 in the launch tube 48, a signal is given to launch the missile or rocket. Initially, valve 22 is in the closed position (shown in FIGURE 1). Operation of the exothermic steam generator 10 requires two separate signals. The first signal initiates the charge reaction by activating switch or starting means '37. The ensuing chemical reaction raises the temperature and pressure of the water or liquid 32 within the vessel 11. A second signal actuates valve motor 42 which raises valve 22 opening outlets 25. The liquid 32 commences to flow through outlets 24 and 25 thus lowering the pressure within vessel 11. This drop in pressure causes the water or liquid 32 within vessel 11 to transform to high pressure steam. The high pressure steam then passes through outlets 24, 25, 26 and 28 to launch missile or rocket 12 from launch tube 48 (the missile or rocket acting as a piston situated within tube 48) to a height of about 150 feet above the ground (see FIGURE 3). At approximately the above height the missile or rocket is propelled to its destination by its own motive system (which is not part of the instant invention).

The launch system of this invention has the basic advantage of simplicity of operation. The system is extremely safe by virtue of the nonexplosive reaction of the exothermic charge and the safeguard against inadvertent launch by the inherent requirement for two independent signals to release the steam which is required to launch the missile or rocket 12.

Although the invention has been described with reference to particular embodiments, it will be understood to those skilled in the art that the invention is capable of a variety of alternative embodiments within the spirit and scope of the appended claims.

We claim:

1. The combination of an exothermic steam generator and a rocket launching tube comprising a pressure vessel for containing a fluid medium, a chamber within said vessel having at least two outlets therein, a rocket launching tube mounted on said vessel directly over one of said outlets and adapted to contain a rocket, at least one charge cylinder containing a charge mounted directly within said pressure vessel, an igniter assembly operably associated with said charge cylinder, said charge cylinder and said igniter assembly being enclosed by a lightweight, water-tight protective covering, a valve located within said chamber adapted to close the other of said outlets in a first position and to open said same other outlet in a second position, and means operably connected to said valve for moving said valve from said first position to said second position after said igniter assembly has been activated in order to launch said rocket from said rocket launching tube.

2. The combination of an exothermic steam generator and a rocket launching tube as defined in claim 1 wherein said pressure vessel comprises an outer shell, an inner shell and an insulating material between said outer and inner shells.

3. The combination of an exothermic steam generator and a rocket launching tube as defined in claim 1 wherein said igniter assembly comprises a starter spread over one end of said charge cylinder, an igniter operably associated with said starter, a starting means and a cable operably connecting said igniter to said starting means.

4. The combination of an exothermic steam generator and a rocket launching tube as defined in claim 3 wherein said pressure vessel comprises an outer shell, an inner shell and an insulating material between said outer and inner shells.

5. A11 exothermic steam generator as defined in claim 4 wherein said protective covering is polyethylene.

References Cited UNITED STATES PATENTS 1,349,969 8/1920 Leathers 12221 X 3,087,451 4/1963 Chandler 60-227 3,088,377 5/1963 Siegel 891.818 X 3,131,597 5/1964 Gram et a1. 89-11818 X 1,035,202 8/1912 Lang 1222.1 X 1,562,137 11/1925 Barnes 102-22 3,049,079 8/1962 Eilo 10224 SAMUEL W. ENGLE, Primary Examiner.

U.S. Cl. X.R. 12221 

